I scored a 20 gallon fish tank on freecycle, and am planning to use the two largest panes to craft a cold frame. I did read the links posted here to various sites w/ cold frame info, but I still have some questions:

1. Does the top of the frame have to be sloped downward?

2. Do all sides have to be glass, or can just the top be glass?

3. Does it have to have a bottom, or can i just do sides and a top and put it on top of seedling pots, wherever I have them outside (on stones, on cement, on a brick patio, etc?).

4. To use for hardening off, I prop the top for a week, and then remove it for a week? Or keep it closed for a week, then propped for a week?

5. For hardening off, do I have to shade the frame, or is the glass enough of a filter for the sun for seedlings raised in the house?

I scored a 20 gallon fish tank on freecycle, and am planning to use the two largest panes to craft a cold frame. I did read the links posted here to various sites w/ cold frame info, but I still have some questions:

Very nice, isn't getting free stuff great. I went to the rental yard today for a few repair parts, and another customer gave me his older Line Trimmer. It's still in great shape.

1. Does the top of the frame have to be sloped downward?

No, but a slope front gives more light or less shadows.

2. Do all sides have to be glass, or can just the top be glass?

Just the top. I would be even better if you insulated the two ends and back. This is why cold frames made of straw bales work so well. Insulation

3. Does it have to have a bottom, or can i just do sides and a top and put it on top of seedling pots, wherever I have them outside (on stones, on cement, on a brick patio, etc?).

No bottom, Yes, to all the rest, although soil is a better insulator. Not sure, the brick and concrete may pull heat out of the box.

4. To use for hardening off, I prop the top for a week, and then remove it for a week? Or keep it closed for a week, then propped for a week?

Prop for a week and removed for a week. If you leave it closed during the day, you could cook the plants.

5. For hardening off, do I have to shade the frame, or is the glass enough of a filter for the sun for seedlings raised in the house?

Shade may be required on the extra hot days. It also depends on what you are hardening. Cool season crops, I would definitely shade.